To study the mechanism by which attachment of trophoblast and uterine cells occurs during implantation, changes in surface proteins will be determined using in vitro tissue culture. Epithelial and stromal cells will be separated from the endometrium by enzymatic methods. Surface proteins of epithelial, stromal and trophoblast cells in culture will be labeled with radioactive iodine and analyzed by single and two-dimensional electrophoresis. Immunofluorescence will be used to determine the presence and distribution of surface fibronectin and possible changes during attachment and invasiveness. Changes in surface binding properties will be determined using radioactive fibronectin. The research will provide fundamental information about the biochemical mechanism of normal implantation of relevance to problems of fertility or infertility and uterine neoplasia.